So on my '09 taco at around 5k I started to notice that the inner area of the tail pipe was black with suit and that there would occasionally be black splatter on my mud flap. I always chalked it up to my K&N CAI and my exhaust. Now on my '11 with around 1000mi i am noticing the same thing. I did a little reading and found that Toyota recommends nothing lower then 87 octane (which i use) but that all tests were conducted with 91 octane. Also i have been getting about 16MPG around town and HWY. Suggested is between 16 town and 20 HWY. The only thing deviant from stock on this truck is the 265/75R16 that I had the dealer switch over from my old truck.

My question is could burning a lower octane then testing cause this effect since higher octane only matters during periods of high RPM? and has anyone else experienced this problem?

Im planing on going to the dealer for a few items and will be having them reset the computer for the tire size and to run a diagnostic.

All vehicles come very rich (fuel) from the factory. The black soot is a good thing. The earlier 2nd gens run smoother and get better MPG with higher octane. (Lots of opinions on this). My take is with higher oct the ecu goes to a more agressive timing map and creating more efficent combustion. I use 93 all the time now.
To test, you could fill up 91or 93, clean the inside of the tail pipe and see if you get the same results as with 87 for 1000 miles.

Cleaning out the tailpipe with an SOS Pad will keep it looking new and wont scratch.. I feel that my wife's Audi that we ran 92 octane in got way dirtier than my Tacoma that I run 87 in... I have always been told that small amounts of soot in a tailpipe are fine.

Cleaning out the tailpipe with an SOS Pad will keep it looking new and wont scratch.. I feel that my wife's Audi that we ran 92 octane in got way dirtier than my Tacoma that I run 87 in... I have always been told that small amounts of soot in a tailpipe are fine.

it's a very sad day when people clean the inside of there exhaust ?????

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No, it's called pride and attention to detail. Most hotrod/classic car owners do this every time the engine is turned over. Personally, I barely give the outside of it a sponge every 2-3 months I wash my truck... but it's also an off road vehicle.

Sounds crazy, but it actually doesn't.. I have done mine many times. When I had my 98 Tacoma, I had some chrome Smittybuilt nerf bars that would rust like crazy after the road salt in the winter.. It was the only thing that would remove the rust and not scratch. Kept them looking like new.